1. Field of the Invention
The present invention relates generally to semiconductor wafer cleaning and, more particularly, a fluid delivery ring to be utilized in semiconductor wafer spin, rinse, and dry (SRD) modules.
2. Description of the Related Art
Wafer preparation and cleaning operations are performed in fabrication of semiconductor devices. In one of such wafer preparation operations, a wafer is spin rinsed in a spin, rinse, and dry (SRD) module. A simplified schematic diagram of an exemplary prior art SRD module 100 is provided in FIG. 1. As illustrated, the SRD module 100 includes a bowl 102 rigidly mounted on an SRD housing 118. The SRD housing 118 has a bore to receive a shaft 117, which is coupled to a motor 116. The motor 116 causes the shaft 117 and thus the spindle 106 and a wafer 104 to rotate in a rotation direction 112. A chuck 110 extends through the bowl 102 and is mounted on a spindle 106. A seal 126 is defined between the spindle 106 and the shaft 117 in order to prevent chemicals from exiting the SRD module. Four spindle fingers 108 coupled to the chuck 110, support the wafer 104 along its edges. In the SRD module 100, the chuck 110 moves vertically in the movement direction 114. As such, the chuck 110 moves upwardly in the bowl 102 such that it extends outside the bowl 102 and above bowl lips 102a. Once the wafer 104 is delivered to the spindle fingers 108 at a level above the bowl lips 102a, the chuck 110 moves downward and back into the bowl 102 such that the wafer 104 is disposed below the bowl lips 102a. 
A backside rinse nuzzle 124 mounted on the inner surface of bottom wall of the bowl 102 sprays liquid (e.g., DI water) onto the bottom side of the wafer 104. A spigot 120 is disposed above the bowl 102 and above the wafer 104. A fluid (e.g., DI water) supplied to the spigot 120 through a tube 122 is sprayed onto the surface of the wafer 104 as the wafer is spun at high revolutions per minute (RPMs). The spigot is designed to move horizontally, in the spigot movement direction 121. At the conclusion of the rinsing operation, the accumulated fluid is drained through the drain port 128 defined in the bottom wall of the bowl 102 as well as the bottom wall of the SRD housing 118. Once the surface of the wafer 104 and the bottom of the wafer 104 are sprayed with fluid, the supplying of fluid is stopped by turning off the spigot 120. Thereafter, the wafer 104 is dried by being spun at high RPMs. As soon as the wafer is dried, the chuck 110 is once again moved upward from within the bowl 102 and is extended to the outside of the bowl 102 and the bowl lips 102a so as to unload the processed wafer 104.
Several problems can be associated with the conventional SRD module 100. One primary concern associated with the conventional SRD module is the use of a single spigot for fluid delivery onto the surface of the wafer. One problem with the use of the single point fluid delivery spigot is that such system fails to yield an optimum rinsing operation as some portions of the wafer may not be exposed to sufficient amount of rinsing fluid. A second major problem is that the use of spigots may result in the recontamination of a processed wafer. This occurs because even after the fluid delivery has seized, excess liquid still remains in the spigot 120. As such, frequently, the excess fluid (e.g., DI water) remained in the spigot 120 flows out of the spigot 120 and drips on an otherwise clean surface of the wafer 104 recontaminating the surface of the processed wafer (e.g., causing stains or particulate spots). When such dripping occurs, the SRD operation must be repeated again (if detected), thereby reducing throughput as a result of increasing the overall time expended in the SRD module. If the problem is undetected, the quality of the cleaning goes down.
Another problem associated with the typical SRD module is having chemically incompatible components. In a typical SRD module, the chuck 110 is usually made out of Aluminum, the bowl 102 is made out of polyurethane, and the spigot is made out of stainless steal. These components may enter into chemical reactions with the fluids introduced into the SRD module. As a consequence, further contaminants may be introduced into the SRD module. For instance, as the chuck 110 moves up and down within the bowl 102, some of its coating flakes off of the chuck thus generating particulates and contaminants inside the bowl 102 and the SRD module 100. These contaminants may react with the residual chemicals (e.g., HF, NH3OH, etc.) present in the SRD module from the previous operation of brush scrubbing of the wafer surfaces. As a result of such chemical reactions between the generated particulates and contaminants of the chuck 110 with the residual chemicals, the wafer 104 as well as the SRD module is recontaminated.
In addition to introducing contaminants, the typical SRD module utilizes a chuck having an extremely complex design. In the conventional SRD module, the chuck 110 moves up and down through the bowl 102 to receive and deliver the wafer 104. As such, it is imperative that the chuck remain properly calibrated so that it comes to rest at the exact orientation. In situations where the chuck is not properly aligned, the failure to properly receive and deliver the wafer, mandates the realignment of the chuck. The process of realigning the chuck is very time consuming and labor intensive. Consequently, in order to realign the chuck, the SRD module must be taken off-line for an extended period of time thus reducing the throughput.
In view of the foregoing, a need therefore exists in the art for a chemically compatible SRD module that enables efficient rinsing of a surface of a substrate without recontaminating the substrate surface.